West Marine representatives say the company’s new Seattle store across from Lake Union will be its premier Northwest location, offering an expanded selection of products and several new services.

The store at 1275 Westlake Ave. will replace the location a few blocks away on Mercer Street, which closed on Sunday. Workers are in the process of moving merchandise and operations to the new store, which opens Sept. 4.

The Westlake store will include 18,000 square feet of retail space, about 50 percent more than the Mercer site, and offer an expanded selection of electronics, maintenance items, fasteners, inflatable goods, engines, plumbing materials and soft goods such as clothing.

General manager Jeff Varvil said the store will also feature a much larger sailing section, which will grow from about half an aisle to two-plus aisles of merchandise, and a much broader variety of lines.

“We probably have, conservatively, at least 50 to 60 different lines to look at, touch, feel, pull on,” he said.

The store will be equipped with a mobile rigging van available for dockside work, and will be one of three West Marine stores nationally to provide a “professional captain’s service” that offers special orders on parts for captains of large vessels. The other stores offering the service are in San Diego and Fort Lauderdale.

The new location, which formerly housed a fitness center, is one of 15 West Marine stores around Washington. A road widening project prompted the move from the Mercer Street site, but Varvil said it also provided an opportunity to revamp the store to better serve customers. The company surveyed customers about what they wanted in the new store, he said, and the feedback made it clear that convenience and selection were top priorities.

“We asked our customers what they wanted, and this is us responding to it,” he said.

The store has an adjoining parking lot, as well as parking on city property across Westlake Avenue. A bike trail runs along Lake Union, making the location more convenient for the approximately half of staffers who bike to work, Varvil said, and its large windows will help cut down on energy costs.

“Everbody’s very, very excited about the move,” he said. “It’s a huge plus for us and for our customers.”